Biology Chapter 2 Quiz

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Questions and Answers

What is the primary hormone produced by the beta cells that are targeted by white blood cells?

Cortisol

Insulin (correct)

Adrenaline

Glucagon

Which of the following components is part of the backbone of nucleic acids?

Nitrogenous bases

Hydroxyl groups

Ribose or Deoxyribose

Phosphate groups (correct)

What feature distinguishes RNA from DNA in terms of structure?

RNA contains two deoxyribose sugars

RNA is always single stranded (correct)

RNA contains Thymine instead of Uracil

RNA has a double helix structure

What characteristic of DNA helps maintain a constant width in its double helix structure?

Purine-pyrimidine pairing Signup and view all the answers

Which statement is true regarding the functional properties of RNA?

RNA can act as enzymes Signup and view all the answers

What distinguishes each element from one another?

The unique type of atom present in it Signup and view all the answers

What is the mass number of an atom?

The total number of protons and neutrons combined Signup and view all the answers

What primarily determines the reactivity of an atom?

The distribution of electrons, particularly in the valence shell Signup and view all the answers

Which of the following statements about isotopes is true?

Isotopes of an element show variation in the number of neutrons Signup and view all the answers

What type of bond involves the sharing of electrons between two atoms?

Covalent bond Signup and view all the answers

Which factor does NOT affect the type of covalent bond formed?

The charge of the atoms involved Signup and view all the answers

What is the smallest unit that can represent an element?

Atom Signup and view all the answers

What type of bond forms when two elements have similar electronegativity?

Nonpolar Covalent Bond Signup and view all the answers

Which particle directly participates in chemical reactions?

Electron Signup and view all the answers

In an ionic bond, what occurs to the electron from the less electronegative element?

It is lost to the more electronegative element. Signup and view all the answers

What do we call a bond that forms due to the attraction between opposite charges?

Ionic bond Signup and view all the answers

Which of the following is NOT a property of water caused by hydrogen bonding?

Ionic conductivity Signup and view all the answers

What happens to the temperature of large bodies of water during the night?

They remain constant due to accumulated solar energy. Signup and view all the answers

What is formed as a result of hydrogen bonding in water molecules?

Surface tension Signup and view all the answers

What charge does an anion carry?

-1 Signup and view all the answers

Which of the following describes adhesion in water?

Water molecules sticking to other polar molecules. Signup and view all the answers

What is the function of ribosomes in a cell?

Read nRNA and build proteins Signup and view all the answers

Which of the following structures is responsible for the synthesis of fats and steroids?

Smooth Endoplasmic Reticulum Signup and view all the answers

What is the purpose of the endospore formation in bacterial cells?

To protect against adverse environmental conditions Signup and view all the answers

What component of eukaryotic cells serves to regulate movement in and out of the nucleus?

Nuclear envelope Signup and view all the answers

Which part of a eukaryotic cell is responsible for processing proteins with a special destination?

Rough Endoplasmic Reticulum Signup and view all the answers

How do the two subunits of a ribosome interact with mRNA during protein synthesis?

They independently bind and then assemble around the mRNA Signup and view all the answers

What are the primary components of a flagellum in eukaryotic cells?

9 pairs of microtubules and 2 central microtubules Signup and view all the answers

What regulates the shape of the nucleus in a eukaryotic cell?

Nuclear lamina Signup and view all the answers

What structure is absent in animal cells but present in plant and fungal cells?

Cell wall Signup and view all the answers

What happens to water when it freezes?

The molecules lock into a rigid lattice. Signup and view all the answers

Which statement is true about weak acids?

They can reversibly release H+ ions. Signup and view all the answers

What role do hydroxyl groups play in organic molecules?

They convey polarity to the molecule. Signup and view all the answers

How does the pH scale work in relation to hydrogen ions?

Each pH unit represents a multiplication or division of 10. Signup and view all the answers

Which carbohydrate type is known for causing rapid spikes in blood sugar levels?

Simple sugars Signup and view all the answers

What defines a saturated fat?

It has no double bonds between carbon atoms. Signup and view all the answers

What is the primary role of phospholipids in cells?

Membrane composition Signup and view all the answers

How are essential amino acids defined?

Amino acids that must be obtained from diet. Signup and view all the answers

What happens to LDL cholesterol in the body?

It tends to stick to artery walls and form plaque. Signup and view all the answers

What defines a polypeptide chain in proteins?

100 or more amino acids linked by bonds. Signup and view all the answers

Which of the following is a characteristic of enzymes?

They lower the activation energy of chemical reactions. Signup and view all the answers

What are the two types of fiber found in carbohydrates?

Soluble and insoluble fibers Signup and view all the answers

Which of the following statements about basal metabolism is accurate?

It accounts for the majority of caloric expenditure at rest. Signup and view all the answers

What type of interaction forms disulfide bridges in proteins?

Covalent bonds Signup and view all the answers

Study Notes

Elements and Atoms

Elements are substances with unique properties, defined by their specific type of atom.
Subatomic particles include protons (positive charge, mass of 1 dalton), neutrons (no charge, mass of 1 dalton), and electrons (negative charge, negligible mass).
Hadrons, such as protons and neutrons, are made of quarks (protons: 2 up and 1 down; neutrons: 2 down and 1 up).
Atomic number indicates the number of protons; mass number equals total protons and neutrons.
Isotopes are variants of elements differing in neutron count; stability varies among isotopes.
Chemical reactivity depends on electron distribution, particularly valence electrons.

Types of Chemical Bonds

Covalent Bonds: Electrons shared between atoms; can be polar (unequal sharing due to electronegativity difference) or nonpolar (equal sharing).
Ionic Bonds: Significant difference in electronegativity leads to electron transfer; forms cations (positive charge) and anions (negative charge).
Hydrogen Bonds: Attraction between partially charged regions of polar molecules; depicted as dotted lines.

Properties of Water

Water (H2O) exhibits emergent properties due to hydrogen bonds.
Cohesion and Adhesion: Cohesion gives rise to surface tension, while adhesion allows water to interact with other polar molecules.
Water regulates temperature, absorbing solar energy to break hydrogen bonds before increasing kinetic energy.
Ice is less dense than liquid water, insulating underlying bodies of water and preventing freezing.
Water as a solvent reacts with solutes to form hydroxide (OH-) and hydrogen ions (H+), maintaining a neutral state.

Acids and Bases

Acids increase hydrogen ion concentration (H+); strong acids completely dissociate while weak acids do so reversibly.
Bases decrease hydrogen ion concentration, either by removing H+ or releasing OH-.
pH is calculated as -log[H+]; decreasing pH corresponds to increasing H+ ion concentration.

Organic Molecules and Functional Groups

Hydrocarbons form life's molecular foundation; pure hydrocarbons are nonpolar and often gaseous.
Functional Groups: Modify hydrocarbon properties, facilitating interactions with water.
- Hydroxyl (OH): alcohols, polar
- Carbonyl (C=O): aldehydes and ketones
- Carboxyl (COOH): acidic properties
- Amino (NH2): basic properties, found in amino acids
- Phosphate (PO4): acidic, involved in energy transfer
- Sulfhydryl (SH): affects protein structure; forms disulfide bridges
- Methyl (CH3): nonpolar, impacts gene expression

Carbohydrates

Composed of monosaccharides (single sugar), disaccharides (two sugars), and polysaccharides (many sugars).
Simple sugars lead to rapid absorption and insulin spikes, while complex carbohydrates provide sustained energy without significant spikes.
Non-starch fibers (soluble and insoluble) serve various digestive roles.

Lipids

Include triglycerides, phospholipids, and steroids.
Triglycerides consist of glycerol plus fatty acids; can be saturated (solid at room temp) or unsaturated (liquid).
Phospholipids are crucial for cell membranes.
Steroids, characterized by a fused ring structure, include cholesterol, which is essential for membrane integrity.

Proteins

Comprised of amino acids linked by peptide bonds; structure dictates function.
Levels of structure: primary (amino acid chain), secondary (alpha helices and beta sheets), tertiary (3D shape), quaternary (multi-polypeptide assemblies).
Essential Amino Acids (EAA) must be ingested as they cannot be synthesized by the body.

Nucleic Acids

Types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), made of nucleotides.
DNA is double-stranded with complementary base pairing (A-T, G-C) and antiparallel orientation; RNA is single-stranded and can fold into unique shapes, functioning as enzymes.
Phosphodiester linkages connect nucleotides, forming long chains.

Diabetes

Type 1 diabetes is autoimmune; the body fails to produce insulin.
Type 2 diabetes results from insulin down-regulation and can often be managed through lifestyle changes.### Antibiotic Resistance and Key Cellular Features
Antibiotic resistance can be associated with the presence of genes for sex pilus, enabling gene transfer between bacteria.

Ribosomes

Ribosomes interpret mRNA and synthesize proteins.
Composed of two subunits distinguished by size and density:
- Large subunit: 50S
- Small subunit: 30S
- Assembled form: 70S
Ribosomes are effective targets for antibiotic action.

Endospore Formation

Endospores are dehydrated cells encased in a protective protein coat.
Formation occurs in response to harsh environmental conditions, allowing survival in unfavorable settings.
Endospores can remain viable for extended periods.
Upon rehydration in favorable conditions, the organism can reactivate, e.g., Bacillus anthracis (causes anthrax).

Eukaryotic Cell Structure

Cell Wall:
- Plant cells: composed of cellulose.
- Fungal cells: include chitin.
- Animal cells: lack a cell wall but possess an extracellular matrix that binds tissues together.
Flagella:
- Located within the plasma membrane and cell wall.
- Consists of a complex structure: 9 pairs of microtubules surrounding 2 central microtubules.
- Moves in a back and forth motion for motility; cilia share a similar structure but are shorter and used for directional movement.
Nucleus:
- Houses genomic DNA and the nucleolus, which contains RNA enzyme genes.
- Surrounded by a double membrane called the nuclear envelope, which connects to the rough endoplasmic reticulum (ER).
- Nuclear pores regulate molecular entry and exit.
- The nuclear lamina provides structural support to the nucleus.
Endoplasmic Reticulum (ER):
- A network of tubules encircling the nucleus.
- Rough ER:
  - Characterized by ribosomes, giving a granular appearance.
  - Responsible for processing proteins destined for specific locations.
  - Plays a role in constructing new proteins.
- Smooth ER:
  - Lacks ribosomes and has a smooth appearance.
  - Synthesizes lipids and steroids, and forms new cell membranes, including phospholipids.
  - Involved in detoxifying non-polar drugs through hydroxylation, making them more easily filtered by the kidneys.
Ribosome Structure:
- Ribosomes consist of two main subunits:
  - Large subunit: 60S
  - Small subunit: 40S
  - Assembled form: 80S.
- Each subunit is composed of both protein and RNA; RNA is synthesized by the nucleolus.
- Ribosome subunits exist independently, and when mRNA is present, they bind based on proximity.
Protein Translation and ER Interaction:
- Ribosomes translate mRNA, facilitating protein synthesis.
- If mRNA encodes specific proteins, the ribosomes associate with the rough ER, releasing synthesized proteins into the ER lumen.
- Once protein synthesis completes, ribosomal subunits, mRNA, and rough ER dissociate.

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Description

Test your knowledge on the fundamentals of biology in Chapter 2. This quiz covers the unique properties of elements, atomic structure, and the different types of subatomic particles. Challenge yourself with questions designed to enhance your understanding of basic biological concepts.